In balancing machines different bearing arrangements for rotatable support are provided for the rotor to be balanced, depending on the type and size of the rotor. Conventional bearing arrangements include, for example, supporting roller bearings in which the rotor is placed on pairs of supporting rollers. Where lightweight rotors are involved, use is made of prism bearings made from a wide variety of materials, the permissible compressive loads per unit area being however low. For lightweight rotors provision can be made for an aerostatic or aerodynamic bearing. At high rotational speeds and with heavyweight rotors, sliding bearings are conventionally used as, for example, hydrostatic or hydrodynamic sliding bearings. As such, the bearings employed are frequently similar or identical to those in operating condition, being accurately designed to fit the bearing journal of the respective rotor.
In a balancing machine of the type initially referred to, which is known from U.S. Pat. No. 1,486,115, the sliding bearing includes two spaced segmental bearing shoes mounted on a support in such a manner as to enable them to execute limited rocking motions. The bearing shoes have passageways terminating in the bearing face and communicating by means of flexible conduits with a supply system for the supply of oil under pressure. On rotation of the rotor held in the bearing, a wedge-shaped oil film carrying the rotor is formed between the rotor and the bearing shoes.
A balancing machine with fluid-supplied sliding bearings is furthermore known from the printed publication B 1420 “Auswuchtmaschinen für Kurbelwellen” (balancing machines for crankshafts) of the Carl Schenck AG of Darmstadt. In this machine, during the measuring run the sliding bearings are lubricated with filtered coolant used for cooling the balancing tool during the balancing operation.
In balancing machines the known sliding bearings supplied with fluid necessitate considerable constructional expenditure because of the need to provide special equipment for splash protection and for encapsulating the fluid supply system relative to the environment.
It is also known to use ceramic materials for the manufacture of the sliding or bearing faces of sliding bearings. From DE 195 26 497 A1, for example, a sliding bearing is known which has ceramic sliding members for the formation of a hydrodynamic lubricant wedge and a counteracting bearing face formed by a ceramic layer. Moreover, sintered composite materials for the formation of mating pairs of sliding bearings are known, with the composite materials having a pore volume sufficiently large to hold oil for bearing lubrication, cf. DE 38 22 919 A1, DE 42 14 877 A1. In the known ceramic bearings or porous bearings the cooperating sliding faces of the bearing partners are each of like or similar material.